Integrate lwk into bullbitcoin-mobile

[i5hi]

Update model and pkg to support a liquid wallet.

Keep functions and types ready for integration in bloc when UI work begins.

[i5hi]

• [x] New/Import Wallet
• [x] Sync
• [x] Balance
• [x] Transactions
• [x] Addresses (Receive)
• [x] Send

[mocodesmo]

not completed yet

[i5hi]

@saiy2k Please test send flow, if we have issues we can address them in lwk-dart, if its all good we can close this issue.